Flight Changi Airport departs from Singapore Changi Airport at 08:00 and arrives at Guangzhou Guangzhou Baiyun International Airport at 12:10.
The flighttime is about 4h 10m. The distance travelled ("as the bird flies"): 1282 Km. So the average speed is roughly 308 Km.
The best day to arrive at Singapore is Sunday and it would be best to avoid Saturday, as prices are on average 1113.07% higher than on Sunday. (Average prices, based on 461871 datapoints.)
We have a lot more statistics for flights SQ 850 and between Singapore and Guangzhou.
